With "Scream 4" hitting theaters today, audiences will see Hayden Panettiere on the big screen contending with all that trademark "Scream" scary stuff: knives, threatening phone calls and creepy masks. But they might not realize that Panettiere, in filming the movie, was drawing on a real-life moment of terror.

"Scream 4" introduces a new set of potential victims -- and potential killers -- to the franchise. Included among these cast members is Hayden Panettiere, who plays Kirby, the smart-mouthed, pop culture-savvy best friend of protagonist Jill (Emma Roberts). Panettiere, who gained some serious geek credit with four seasons on "Heroes," admitted that starring in a sequel to a series she grew up loving seems surreal. "I was a huge fan of the franchise," she said. "Shouldn't I just be watching this movie? I could never imagine myself on screen with Neve Campbell."

Speaking to reporters about her experiences filming "Scream 4," Panettiere explained that she was able to relate to the feeling of being alone and scared in a dark house as a result of a real-life incident. "I actually had an experience where I thought someone was breaking into my house," she said. "And that has got to be the most terrified I have ever been in my life."

Panettiere continued: "The fear [was intense], especially as a female in a house by yourself. There happened to be a blackout in the area I was living in, so my alarm was going off and going off and nobody was coming. You go into this survival instinct -- what a person would do when they feel like their life is in jeopardy … I don't know how I managed to do this, but I found myself in my bathroom with my TASER -- I do have a TASER -- and my panic button. It's the most terrifying experience I've had in my life. That desperation. That not knowing who's going to come or what's going to happen or what you're going to do."

And then she reached the thrilling conclusion: "What really happened was that I thought someone was breaking in, and I may have overreacted a little bit in the beginning. I grabbed my TASER and my phone and wound up crawling out my window to find five or six guns with the laser beams pointed at me. And I was running with my TASER and shouting, "Don't shoot me! Don't shoot me! It's my house!" So [the police] did eventually come, but they almost shot me. I'm not joking!"

And Panettiere also wasn't joking when she said "Scream 4" would really deliver the scares. Having had a taste of real-life fright, shouldn't she know?